1404 
Physics. — “Magnetic Researches. VIII. On the susceptibility of 
gaseous oxygen at low temperatures”. By H. KaMertincu ONNES 
and E. OosrerHuis. (Communication N°. 134d from the Physical 
Laboratory at Leiden.) Communisated by Prof. H, KAMERLINGH 
ONNES. 
§ 1. The susceptibility of compressed oaygen between 17° C. and 
temperatures near the critical temperature of oxygen. In our last paper 
in connection with our investigations of various cases in which a 
molecular field of Wetss with opposite sign can be assumed with 
paramagnetic substances, we mentioned the continuation of the 
experiments by KAMERLINGH ONNEs and Perrier which have already 
been projected and the continuation of which may soon be expected, 
and which have for their object to investigate the influence, with 
oxygen, of bringing the molecules to various densities upon the 
deviations ‘from Cvcrin’s law. Working in the same direction, we 
have endeavoured to ascertain whether in gaseous oxygen below the 
-ordinary temperature and above the critical temperature a 4 appears. 
For this purpose we have measured the susceptibility of oxygen 
between 17°C. and —126°.7 C. We used the attraction method in 
the same form as deseribed for the paramagnetic salts in our previous 
paper. A copper tube, closed underneath, 10 em. long, 8 mm. 
external and 6 mm. internal diameter, provided with a capillary 
tube above, by which it could be tilled with oxygen under pressure, 
and closed, one time with a fine tap in which the capillary tube 
ended, another time by pinching this capillary, and then soldering 
up after it had served for filling, was filled with oxygen at ordinary 
temperature to 100 atmospheres. The experiment was then repeated 
with the evacuated tube in the same baths. For results: (see table I 
p. 1405). 
The experiments should be regarded as comparative for the question 
under consideration, but the absolute value of the susceptibility was 
also determined at 289°.9K. It corresponds pretty well to that of 
Weuiss and Piccarp. As manometer we used a metal manometer 
which was compared with a hydrogen manometer going to 120 
atmospheres. The density of oxygen was taken from Amaaar. 47 
appears to be constant, within the limits of accuracy (which is about 
1°/) as far as the boiling-point of ethylene (169°.6 K.). The two 
points in ethylene,. evaporating under reduced pressure, deviate a 
little,- but this need not be considered as of much importance, as 
these temperatures were not accurately known. Moreover the proximity 
